From b399146e3f2cfaa65df473711f43219d12e551f1 Mon Sep 17 00:00:00 2001
From: Carpe-Wang <wangcarpe@126.com>
Date: Wed, 8 Nov 2023 01:17:44 +0800
Subject: [PATCH 1/2] validating the date format, add test case, since
 NumberFormatException extends IllegalArgumentException, it is only necessary
 to write IllegalArgumentException.

---
 .../main/java/com/google/gson/GsonBuilder.java  | 10 +++++++++-
 .../gson/internal/bind/util/ISO8601Utils.java   |  6 +-----
 .../functional/DefaultTypeAdaptersTest.java     | 17 +++++++++++++++++
 3 files changed, 27 insertions(+), 6 deletions(-)

diff --git a/gson/src/main/java/com/google/gson/GsonBuilder.java b/gson/src/main/java/com/google/gson/GsonBuilder.java
index 536207362f..7ebdad4e30 100644
--- a/gson/src/main/java/com/google/gson/GsonBuilder.java
+++ b/gson/src/main/java/com/google/gson/GsonBuilder.java
@@ -43,6 +43,7 @@
 import com.google.gson.stream.JsonWriter;
 import java.lang.reflect.Type;
 import java.text.DateFormat;
+import java.text.SimpleDateFormat;
 import java.util.ArrayDeque;
 import java.util.ArrayList;
 import java.util.Collections;
@@ -598,7 +599,14 @@ public GsonBuilder disableHtmlEscaping() {
    */
   @CanIgnoreReturnValue
   public GsonBuilder setDateFormat(String pattern) {
-    // TODO(Joel): Make this fail fast if it is an invalid date format
+    if (pattern != null) {
+      try {
+        new SimpleDateFormat(pattern);
+      } catch (IllegalArgumentException e) {
+        // Throw exception if it is an invalid date format
+        throw new IllegalArgumentException("The date pattern '" + pattern + "' is not valid", e);
+      }
+    }
     this.datePattern = pattern;
     return this;
   }
diff --git a/gson/src/main/java/com/google/gson/internal/bind/util/ISO8601Utils.java b/gson/src/main/java/com/google/gson/internal/bind/util/ISO8601Utils.java
index 4f08b039b3..bf7b7c19b2 100644
--- a/gson/src/main/java/com/google/gson/internal/bind/util/ISO8601Utils.java
+++ b/gson/src/main/java/com/google/gson/internal/bind/util/ISO8601Utils.java
@@ -287,11 +287,7 @@ public static Date parse(String date, ParsePosition pos) throws ParseException {
       return calendar.getTime();
       // If we get a ParseException it'll already have the right message/offset.
       // Other exception types can convert here.
-    } catch (IndexOutOfBoundsException e) {
-      fail = e;
-    } catch (NumberFormatException e) {
-      fail = e;
-    } catch (IllegalArgumentException e) {
+    } catch (IndexOutOfBoundsException | IllegalArgumentException e) {
       fail = e;
     }
     String input = (date == null) ? null : ('"' + date + '"');
diff --git a/gson/src/test/java/com/google/gson/functional/DefaultTypeAdaptersTest.java b/gson/src/test/java/com/google/gson/functional/DefaultTypeAdaptersTest.java
index 770996f92f..96a30a9455 100644
--- a/gson/src/test/java/com/google/gson/functional/DefaultTypeAdaptersTest.java
+++ b/gson/src/test/java/com/google/gson/functional/DefaultTypeAdaptersTest.java
@@ -16,6 +16,7 @@
 package com.google.gson.functional;
 
 import static com.google.common.truth.Truth.assertThat;
+import static org.junit.Assert.assertThrows;
 import static org.junit.Assert.fail;
 
 import com.google.gson.Gson;
@@ -737,6 +738,22 @@ public void testStringBufferDeserialization() {
     assertThat(sb.toString()).isEqualTo("abc");
   }
 
+  @Test
+  public void testSetDateFormatWithInvalidPattern() {
+    GsonBuilder builder = new GsonBuilder();
+    String invalidPattern = "This is a invalid Pattern";
+    assertThrows(IllegalArgumentException.class, () -> {
+      builder.setDateFormat(invalidPattern);
+    });
+  }
+
+  @Test
+  public void testSetDateFormatWithValidPattern() {
+    GsonBuilder builder = new GsonBuilder();
+    String validPattern = "yyyy-MM-dd";
+    builder.setDateFormat(validPattern);
+  }
+
   private static class MyClassTypeAdapter extends TypeAdapter<Class<?>> {
     @Override
     public void write(JsonWriter out, Class<?> value) throws IOException {

From bb8c45dab0d4a5da06d9eaf0f72e78da27857ab1 Mon Sep 17 00:00:00 2001
From: Carpe-Wang <wangcarpe@126.com>
Date: Sun, 19 Nov 2023 01:38:38 +0800
Subject: [PATCH 2/2] Apply code formatting with Spotless

---
 .../google/gson/functional/DefaultTypeAdaptersTest.java   | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/gson/src/test/java/com/google/gson/functional/DefaultTypeAdaptersTest.java b/gson/src/test/java/com/google/gson/functional/DefaultTypeAdaptersTest.java
index 7475cae440..ccef12229c 100644
--- a/gson/src/test/java/com/google/gson/functional/DefaultTypeAdaptersTest.java
+++ b/gson/src/test/java/com/google/gson/functional/DefaultTypeAdaptersTest.java
@@ -742,9 +742,11 @@ public void testStringBufferDeserialization() {
   public void testSetDateFormatWithInvalidPattern() {
     GsonBuilder builder = new GsonBuilder();
     String invalidPattern = "This is a invalid Pattern";
-    assertThrows(IllegalArgumentException.class, () -> {
-      builder.setDateFormat(invalidPattern);
-    });
+    assertThrows(
+        IllegalArgumentException.class,
+        () -> {
+          builder.setDateFormat(invalidPattern);
+        });
   }
 
   @Test